To be effective at nutrient removal, aquaponics systems should be sized correctly to balance nutrient
production from fish culture and nutrient uptake by plants. We describe a method where the plant
component was isolated from the fish rearing operation so that nutrient removal could be evaluated
independently. Two crops, lettuce (Latuca sativa) and nasturtium (Tropaeolum majus), were evaluated.
Nasturtium had higher removal rates and removed both total ammonia nitrogen (TAN) and nitrate resulting
in 80% DIN removal while lettuce removed only 48%. Lettuce removed only TAN and was ineffective
at nitrate removal. Older plants were more effective at DIN removal while younger plants were more
effective at PO4 removal. When normalized for biomass, younger plants had much higher removal rates.
These results demonstrated that both crop and cropping method have considerable impacts on nutrient
removal. This method will allow operators to adjust their system quickly and easily to meet remediation
goals.
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